Expression of NOS–2, COX–2 and Th1/Th2 cytokines in migraine

Nitric oxide (NO) probably plays an important role in the pathogenesis of migraine without aura (MWA). As the activation of NO–ergic cascade has been shown to be closely linked to cyclooxygenase pathway and to cause some differences in peripheral blood lymphocyte populations, we investigated if the Th1/Th2 balance in peripheral blood of MWA patients was affected in comparison to controls. Twenty–six MWA patients and 10 healthy controls (C) were enrolled in this study. Blood samples were taken at baseline (T0) and during an induced migraine attack (T1). Total RNA from human peripheral blood lymphocytes (PBLs) was isolated and reverse–transcribed to prepare complementary DNA. COX–2, NOS–2 and β–actin were amplified using PCR. PBLs from patients and controls were stimulated with phorbol 12–myristate 13–acetate plus ionomycin in the presence of brefeldin A. Cells were surface–stained with fluorochrome–conjugated anti–CD3 and anti–CD8 monoclonal antibodies (mAbs) and intracellularly stained with fluorochrome– conjugated anti–IFN–γ or anti–IL–4 mAbs. The level of cytokine expression was analyzed by gating on the CD4+ lymphocyte subset. Th1 and Th2 type cytokines (IFN–γ, IL–2, IL–4) were directly assayed in serum by ELISA. Preliminary results indicate that NOS–2 was upregulated in MWA patients at basal time if compared to controls, whereas after NOD administration NOS–2 was significantly decreased. COX–2 was upregulated in MWA patients at basal time and it had an opposite trend after NOD administration. The homeostatic Th1/Th2 balance defined by the IFN–γ or IL–4 cytokine expression was unchanged in MWA patients in comparison to controls, and NOD administration did not affect that pattern. The cell activation machinery was not altered after mitogenic activation, as shown by CD69 expression level. Cytokine serum levels showed no significant changes in all studied situations. This study confirms the relevance of the NOS/COX system in MWA but, in contrast with previous studies, excludes their effect and activation on peripheral cytokine production. More sophisticated experimental models are needed to investigate the ability of NOS/COX to activate migraine pain.